Separation of metallic sulfids from ores.



T. M. OWEN. SEPARATION OF METALLIC SULFIDS FROM ORES.

APPLICATION FILED H8127. I914.

Patented Oct. 19, 1915.

ammo o T M. Owen elm;

1 I I I I I I I 1 I I I n a u l W M w UNITED STATES PATENT OFF -a'nomas MACKELLAR owEN, 0F SYDNEY, NEW SOUTH wALEs, AUSTRALIA, ASSIGNOR T0 EDWARD WILLIAM CULVER, or SYDNEY, NEW-SOUTH WALES, AUSTRALIA.

S PARATION OF M TALLIC sULEIDs FROM ORES.

1 Specification of Letters Patent.

Application filed February 27, 1914. Serial No. 821,473.

To all whom'z't may concern.

Be it known that I, THOMAS MACKELLAR OWEN, subject of the King of Great Britain and Ireland, residing at 116 Clarence street, Sydney, New South Wales, Australia, late of Broken Hill, in said State, have invented certain new and useful Improvements in the Separation of Metallic Sulfids from Ores, of which the following is a specification.

This invention relates to the preferential or selective separation by froth flotation of mixed-metallic sulfids from ores containing them, and in particular to the preferential or selective separation of lead sulfids (galena) and zinc sulfids (blende).

The process though primarily useful in the treatment of weathered slimes is applicable to slimes. and like ore productsgenerally and the'term slimes is used in this specification to include all such products.

The process is based on the discovery that small quantities of certain manganese salts applied to the slimes alter or modify their behavior in flotation treatment so that the sulfids may be obtained separately, that is to say, so that separate products may be obtained each of which respectively is relatively high in one particular sulfid and relatively low in other sulfids.

In the froth flotation treatment of mixed sulfid ores containing, for' instance, lead, copper, zinc, and iron sulfids, or any two or three of those sulfids, the introduction of a small quantity of an alkaline permanganate into contact withthe slimes makes the flota:

tion action selective in the case of a large range of representative slimes. In the case of lead-zinc slimes the galena and the blende are raised in successive order; the galenais floated first, the bulk of the silver (if present) accompanying the galena, and the blende is subsequently floated from the residue after acid has been added to the pulp. If copper is with the lead. 1

The proportion of alkaline permanganate required is less than the quantity which would be necessary to change permanently the reducing character of the'mass of-the pulp. Relatively minute quantities of free alkaline permanganate will substantially af feet the behavior of certain metallic sulfids in the flotation liquor.

My process depends upon change of chartralize its reducing present it usually comes upacteristics in the slime constituents andre-' qulres that the permanganate shall, before or during its dissoclation, act'on the slimes. The pretreatment of the water used in sulfid flotation processes by the addition thereto of alkaline permanganates such as potassium permanganate in. sufficient quantity to neu quality does not procure the same eflects.

In operating my process it is most advantageous to add the alkalinepermanganate Patented Oct. 19, 1915. a v

after the slimes have been mixed with the flotation liquor; if added to the-liquor before the liquor is brought into contact with the slimes more or less of the alkaline permanganate is wasted in reacting with reducmg elements contained in the Water, which must be satisfied'before alkaline permanganate is available for acting on the slimes constituents; and this wasteful excess of permanganate has the effect of more quickly sickening the circuit liquor. (Manganese .dioxid may be used to procure effects of the same order as alkaline permanganates.) The pulp usually contains from three to four weights. of water for every one weightof slimes, but experiment has demonstrated that this proportion may be substantially varied, as the effectiveness of' the process does not depend upon any certain fluidity of pulp within extreme limits, so long as a? freely flowing pulp is used, asin known sulfid flotation processes. In this specification the term pulp is used to designate the mixture of slimes and water.

The frothing agent most suitable for use in practice is eucalyptus oil, but I do not confine myself to the use of eucalyptus oil as a frothing agent.

The eflectiveness of the process is not normally dependent upon its conduct at a certain critical temperature, and my experiments indicate that it may be conducted in .practice at any normal atmospheric temperature or at an elevated temperature. When, however the slimes are of a highly reducing characterand act to very rapidly decompose the permanganate, it is advantageous to conduct the process at a temperature approximately 120 F.

In order to determine the quantity of potassium permanganate or other alkaline ermanganate, or manganese dioxid, requlred -eucalyptus oil per ton of slimes, .centrate was obtained containing: 60.5%

. taining zinc may to procure the best effect, a closedseries of tests-may be made. As every or'e and-ore product varies moreor less in constitution, a definite proportion applicable with best effect cannot be specified for general uses without reference to the nature of .the material to be treated. By way of example,

however, I quote the case of a weathered slime obtained from the treatment of more obtained at Broken Hill, New South Wales, said slime containing approximately by assay 16% lead, 13%% zinc, and 17 oz. silver per ton. In this treatment, using 2% lbs. of potassium permanganate, and 3 oz. of

a. lead conlead, 54 oz. silver and 11.8% zinc, and, after adding lbs. of sulfuric acid per ton of original slimes, a zinc concentrate containing 6.2% lead, 11.2 oz. silver, and 43.4%

zinc, leaving a residue containing 2.0% lead,'

3.0 oz. silver, and 1.6%;zinc.

In some cases I findt advantageous to introduce into the pulpasalt which has the effect ofdeadening the 'flotative properties of certain constituents of the slimes. Such deadening agents are well known and are in use. It is advantageous tomodify the-action of the flotation medium'inthis' froth flotation with acid for the recovery of'zinc.

- In carrying out my said invention upon a v weathered slime of the constitution previously defined, obtained at Broken I-Iill Junction North mine, New South Wales, I

proceed by introducing the slime into substantially fresh water free from acid; agitate; add free potassium permangante; add the frothing' agent'to the pulp (which contains usually 3-4 parts by weight of water to one part of slime) and then submit the mixture to froth flotation according to known practice (without acid), with the re-.

sult that' 'the lead sulfids float, as also does the silver present, leaving the. zinc in the residue. The residue .is then resubmitted to froth-flotation, after acid, (about 15 lbs. sulfuric acid per ton of slimes), has been added thereto, with the result that the zinc is floated. I r

If acid in any material quantity be added to the pulp before the lead is separated the 1 selective effect is not procured and the zinc is flotated with the lead and silver, a collecnitely ti-ve float instead of a selective float being obtained, which (collective) result is notthe' object of my invention.

In practice it is desirable to circulate the treatment liquor. In this event I take care to preserve the lead flotation liquor as far as practicable from contamination with the zinc flotation liquor. For this purpose I arrange to use two storage tanks. The first tank I keep replenished with fresh water, and return to 1t the liquor decanted after flotation of the lead. From the second tank is drawn the liquorforretreatment of the deleaded slimes for zinc separation, and the waste liquor is returned to this tank after the zinc has been floated. There are thus two circuit liquors used, the first one being maintained clear of the second; a small quantity of the first circuit liquor is carried into the second liquor, but that is of no consequence. If only one circuit liquor were used for all the operations, the successful results otherwise attamable would be minimized.

Though all the steps in the process may be conducted with the same liquor, replenished to make good the losses, it is found that repeated reuse of the one body of liquor is undesirable.

I find in operating the process in circuit, that the circuit liquor becomes aged after I repeated flotations, and then displays a tendency to bring ahigher proportion of zinc into thelead float, thus reducing the grade of the lead concentrateobtained.

Accumulation of reducing salts. from the slinies inthe clrcuit liquor when used, re-

peatedly minimizes the efliciency of the separation of the first flotation products. It is therefore desirable to keep thev first tank replenished with fresh water. It is undesirable and wasteful. to neutralize these reducby adding oxidizing reagents; by the same valuable effects would are obtained by the use ing salts doing so not be procured as of fresh water in the make-up Ofth first In certain cases, which cannot be deficlassified, I have found the process commercially ineffective for the selectlve separation of copper and iron, though 1n many other cases I have found 1t profitable to use it for the 0 products. In every case therefore 1t needs to be determined by simple laboratory test whether a particular copper-iron slime is subject to commercially successful treatment by the process.

separation of those In'the case of many slimes it is found that i a preliminarv 'weathering even of a few hours duration insures better .resultsoperating the process, and it is therefore desirable to make tests to determine in particular cases if such preliminary weathering treatment is, advantageous.

The physical effects which occur in flotation treatment of mixed sulfids are irregu-I lar and imperfectly understood, as is. well recognized, and it is hence necessary to determine by laboratory tests the characteristics of particular slimes before submitting them to treatment on a commercial scale.

It is desirable in making tests for any of the purposes beforementioned that wet or damp slimes should be treated. Commercially, the .slimes requiring treatment are in a damp or wet condition. A test on slimes which have been dried will not necessarily give effective results, where, under the same conditions, an undried slime may show satisfactory behavior in the process.

Referring now to t he jdrawing, which illustrates moreor less diagrammatically on a convenient and. suitable form of appara-.

tus for carrying out the improved process, the plant consists of a receptacle A. open at the top end and pointed or coned at the bottom. At the top ofthis vessel is attached launder B into which the concentrate overflows and is collected. Into the top of the vessel can be placed, if required, a baffle, or set of baffles, for the purpose of restricting the area of the overflow. Such abaflle is shown at C. At any suitable position in the vessel can be placed one or more screen plates D, for the purpose of steadying down the swirling actions, or currents, caused by the agitation of the pump E hereinafter described. The presence of these screens is an advantage but it is not essential. A vessel F, of a-suitable size is also provided in which the ore. pulp can be given a bath or preliminary treatment, with the permanganate before delivery into the. vessl A. The vesse'l F can consist of a containing tank in which are placed stirring arms G, fixed to a shaft H arranged with means to revolve at suitable speeds. An opening is provided in the lower part connected one end of .a pipe I, connecting at its other end to a centriIugal pump E. A valve K is placed in the pipe I and the rate of flow of the pulp from the vessel F to the pump E, is regulated thereby. Into the pipe I between the valve K and the pump E pro ects a small pipe L with a control valve M, th1s pipe and valve being for the purpose of admitting air in any desired quantities. The plpe 'L is connected either to the open atmosphere or to a supply of compressed air. Only one. of these connections of course would be used at any one time, the choice being decided by the requirements of the of the vessel F to which is plant. The outlet side of the pump E is connected to the vessel A by the pipe which extends "some distance up into the vessel A through the bottom thereof as shown. The pulp is' drawn from the vessel F into the pump E and in its passage through the pipe I the flow either sucks in through the valve M and pipe L the requisite quantity of air, or else the requisite quantity ofair is forced in from the compressed air supply. The frothing agent is added either to the vessel F or through the air pipe. The action of'the pump is to churn the mixture of pulp, air

bottom .of the vessel A and is drawn off through the pipe 0 the rate being regulated by the valve The tail pipe 0 can connect through another pump (or pumps); to another vessel (or series of vessels) as indicated in, the dotted portion of the drawing; in which case the operations performed in the vessel A can be repeated until the tailing is either sufliciently free from leadto go on to the zinc treatment or else sufficiently free from both lead and zinc, or other valuable metals, to be run to waste.

What I claim as my invention and desir to secure by Letters Patent is 1. In selective or preferential froth fiotation separation of metallic sulfids from slimes, the herein described process for augmenting the fiotative quality of certain sulfids in relation to certainother sulfids, which consists in adding to and agitating with the pulp a limited proportion of alkaline permanganate.

permanganate in solution, agitating. the 'sllmes in water containing a flotation medium, removing the leady float concentrate, adding acid, re-agitating and removing the zincy float concentrate.

In testimony whereof I have aflixed my signature in presence of two witnesses.

THOMAS MACKELLAR OWEN. Witnesses:

W. I. 'SrRUs'AR, HAROLDA. Roman. 

